Electric plug adapter



June 22, 1948.

Filed July 19, 1946 1 5 1 ,H/ i Z O wn l mfl fl 1 N M m w Q r 0/. 5 1 w T 77% m. w 5 2 z 1 m R Paten tcd June 22, 1948 ELECTRIC PLUG ADAPTER William J. Miller, Toledo, Ohio, assignor of 'onehalf to 0. Tracy La Cost, Toledo, Ohio Application July 19, 1946, Serial No. 684,832

6 Claims. (Cl. 113-343) My invention relates to devices for making an electrical connection as between a source outlet and a disconnectable service line. The invention particularly relates to a device having means op erative to compensate for the degree of disadiustment or misalignment as between the contacts of I a, source outlet receptacle and a service plug, re-

sulting from wear, long use or flash-arcing and burning which ofttimes makes electrical connection between the two impossible or haphazard. The invention has for its primary object, therefore, to provide an electric plug adapter having means which automatically compensates for such disadjustment and assures electrical connection between the outlet receptacle and service plug.

Another object of the invention is'to provide an electric plug adapter having a compensating means of the character mentioned which is operated by the forces incidental to the act of establishing a physical connection; between the adapter, the source outlet receptacle and the service plug. Specifically, the compensating means of my invention is operated by the forces exerted by the contacts of the source outlet, receptacle and service plug as the adapter is placed in physical connection therewith.

Another object of the invention is to provide an electric plug adapter of simple and inexpensive form but of exceedingly high efficiency and capability to establish positive electrical connection between a source outlet and a service plug.

The invention consists in other features and advantages which will appear from the following description and upon examination of the drawings. Structures containing the invention may partake of different forms and still embody the invention. To illustrate a practical application of the invention, I 'have selected an electric plug adapter as an example of the various structures and details thereof that contain the invention and shall describe the selected structure hereinafter, it being understood that variations may be made without departing from the spirit of the invention. The particular structure selected is shown in the accompanying drawing and described hereinafter.

Fig. 1 of the accompanying drawing is a perspective view of an electric plug adapter which embodies my invention. Fig. 2 is an elevational view of the adapter shown in Fig. 1, a part of the housing case being shown removed to facilitate a showing of the interior thereof. Fig. 3 is a perspective view of one of the contacts of the adapter shown in Fig. 1. Fig. 4 is an enlarged sectional view of a portion of the housing case and a contact in its installed position and somewhat diagrammatically relative to parts of a source outlet and service plug, each shown in broken lines in this figure.

It is commonplace in the field of electrical distribution to provide a source outlet or receptacle which has contacts adapted to mate withthe contacts of a service line plug, whereby the electrical power may be conveyed from a source to an electrical motor, appliance or other useful means connected to the plug. The mating of the contacts of the receptacle and service plug, essential to the transmission of electrical" power, is effected by reason of the fact that the male prongs of the plug are designed in dimension, form and position relative to the dimension,

form and position of the receptacle contacts as to cause a slight relative displacement of the contacts as the plug and receptacle are manually brought together. The yielding resistance relatively exerted by the contacts to such displacement generates forces within the contacts tending to urge the contacts of both into greater intimacy and good electrical conductive relation. However, after a period of use the contacts, by virtue of wear, fatigue or misuse become flabby in their resilient reaction to displacement or become bent or are burned out of the designed interrelation so that electrical connection between service plug and source outlet receptacle becomes impossible to effect. The user thereupon must bear the expense and delay incidental to the removal and replacement of the service plug, outlet receptacle or their contacting parts. l

The electric plug adapter of my invention eliminates the need for such expense and delay and by connection with the outlet receptacle and service plug therewith automatically compensates for whatever fault that may prevail in either plug or receptacle, assuring immediate electrical conduction between the two.'

The fundamental elements of the electric plug adapter of my invention are the connectors, one end of each of which is formed to be inserted into an outlet receptacle and the other end is formed to receive the male prong of a service plug. 'Each connector is provided with contact portions at both ends, each of which reacts with the contacts of the outlet receptacle or service plug then engaging the particular end to distort the opposite end of the adapter connector and position the contact thereof in a position.

to assure electrical connection between said opposite end contact and the contact of the service plug or outlet receptacle engaging the same. Ex-

pressed in another and more specific manner, each connector of the adapter of my invention has contact portions at either end which define dimensionally the effectiveness of the respective contact ends to cause relative contact-makupon connection of the three elements. Upon engagement of the male prong contacts of the service plug with the contact portions of the plug adapter, its connector is distorted and the contact portion thereof designed to engage the contacts of the outlet receptacle are moved. The distortion and movement are in a direction and to an amount that although thecontacts of the receptacle may be bent or flabby byreason of long use, there will nevertheless. be an assured electrical contact established between the adapter and receptacle contacts.

If, on the other hand, the fault is in the prongs oi the service plug, rather than the contacts of the outlet receptacle, the engagement between the contacts of the adapter and outlet receptacle effects a distortion of the adapter connector to position the contacts thereof designed to engage and electrically connect with the prongs of the plug in :a position to effect such engagement and connection notwithstanding the fault. Faults in both service plug and outlet receptacle are likewise compensated for, each to the degree required in the particular situation. Where no fault is present in either service plug or outlet receptacle, the connector of the adapter assures of good and balanced contact pressures with and between the contacts of the service plug, outlet receptacle and the electric plug adapter.

Referring to the drawing and to the particular adapter shown therein, it will be noted that a housing case I formed from molded plastic or some other suitable dielectric material encloses connectors embodied in the two conductors II of opposite polarity. The conductors Il may be formed from fiat strip stock which has been bent and tempered to provide the desired and hereinafter described form and characteristics. Since both conductors are substantially identical in form and characteristic it should sufllce to par ticularly describe one of them.

The conductor llis a double ended unit, in the sense that one end I5 forms a male plug prong contact and the other and I6 constitutes female receptacle contacts. The conductor is formed by bending a length of flat metal strip stock upon itself at I! to form'a pair of slightly spaced, substantially parallel extending and resiliently constrained leg parts I9 and 20. The bend I1 is preferably of such character and radius that the tempered resiliency is not materially effected and the legs I9 and 20 may move toward and away from each other through the intervening space with a yielding constraint about the bend I1.

The leg I9 forms one side and the leg 20 the other side of the male plug prong contact at the end I5 and of the female receptacle contacts at the end I6. The leg I9 also has means which operates to retain the conductor II in an installed position within the case I0. Such means comprises a spur 2| and a foot 22.

The spur 2| is formed by bending a portion of the leg I9 sharply upon itself at 23. Thetwo parallel extending portions 24 thus formed extend angularly to the major plane of extension of the leg I9, preferably at an angle of 90. The foot to form a nearly approximate 90 hook.

The leg 20 carries the primary contacting and operating cams of the conductor of the adapter.

Proximate to the male plug end I5, the leg 20 has a cam portion contact 25. The cam is formed preferably by bending a portion of the strip forming the leg 20, as at 26, obliquely away from the major plane of extension of said leg, again at 21, toward the said plane and, again at 28, along said plane. Spaced from the cam portion the leg 20 is bent, dog-leg as at and 3|, to form a shoulder 32 and a foot 33. By reason of the dog-leg bend of the leg 20, the foot 33 is disposed in parallel relation to that portion of the leg I9 between the [foot 22'and spur 2| but in greater spaced relation than that between the legs I9 and 20 where they form the male plug prong end I5.

The foot 33 of the leg 20 has a cam portion which is embodied preferably in the dimple contact 35 which extends toward the leg l9. The terminal of the leg 20 has a retaining and guiding toe 36 which is formed by'bending said terminal end of the foot 33 to form a substantially 90 hook.

The case I0 is suitably chambered to permit installation of the contacts I! therein. It should suffice to describe the chambering of case I0 required to install one conductor II, as such is duplicated to accommodate the other conductor.

A passageway 40 of slot-like cross section is formed in the case and has an opening 39 through which the male plug prong end I5 is to extend. In cross section, the passageway is of the approximate length of the width of the strip forming the conductor I I and of a width slightly greater than the thickness of the strip forming the legs I9 and 20- and their intervening space.

Inwardly from the exterior face of the case I ii and the opening 39 and communicatin at substantially right angles with the passageway 40, a recess M is formed. The recess 4| extends into the core 420i the case and is sized and configured to receive the spur 2 I, of the leg I9 snugly therein, The edges 43 of the recess 4| form retaining shoulders which operate in conjunctionwith the portions 24 to retain the conductor II against axial movement in the case Ill, as will be hereinafter described. In spaced relation from the recess 4| and along the passageway 60 of approximately a distance as that between the spur 2| and foot 22 of the leg.l9, a second reces 65 is formed in the core 42 of the case.

The recess 45 extends at right angles to the line of the passageway 40 and is sized and configured to receive the foot 22 therein. The side walls of the recess 45 operating in conjunction with the lateral surfaces of the foot 22 assist the spur'2l and recess AI in resisting axial displacement of the conductor II within the case I0.

On the side of the passageway 40 opposite to that from which the recesses ll and 45 extend, a chamber 41 is formed in the case Ill. The chamber 41 has an inner end wall 48 and an outer end wall 49 proximate to the opening 50 in the case l0 aligned with the passageway 40. The space between the wall 48 and'the wall 49 is sufficient to accommodate the foot 33 of the leg 20 in its entire length and permit movement thereof toward and away from the leg IS. The surface of the wall 49 operates as a slide bearing to the movement of the toe 36 during such movement of the foot 33 relative to the leg I9.

Referring specifically to Fig. 4..cf the drawing.

it will be observed that in operation, the male plug prong contact end It is inserted into a conventional source outlet receptacle R and engages the conventional contact C thereof. The crena 25 of the leg 20 and the leg I9 engage facing surfaces of contact C. The spacial relation of thesefacing surfaces of the contacts C causes the legs I 9 and 20 to be pinched together toa degree determined by said spacial relation. The movement of the legs l9 and 20 toward each other is yieldingly resisted by the resistance of the material from which the conductor H is formed, particularly the portions thereof in the vicinity of the bend l1, and by the counteraction produced upon insertion and placement of the male prong J of the conventional service plug P into engagement with the end It of the conductor II.

In the insertion of the prong J. the surfaces thereof are engaged by the leg [9 and the dimple 3."! on the leg 20. The engagement of the dimple 35 with the surface of the prong J causes the legs I9 and 20 to spread relatively against the resistance exerted at the bend l1 and the afore said pinching action produced by the contact C of the receptacle R. Thus, it will be immediately apparent that a balanced pressure will be exerted through the body of the conductor ll tending to effect intimate electrical contact of the legs l9 and 20 with both the prong J and contact C. The pressure thus exerted will automatically compensate for any existent disalignment or disadjustment in position of the prong J with respect to the contact C.

In the event no such fault exists, the pressure exerted by the legs- I!) and 20 of the conductor on the prong J and contact C is of a desired balance assuring a safe interlocking of the-service jack P and outlet receptacle R. In this latter connection, the dimple 35 is preferably formed, as to position and dimension, so as to partially engage in the opening, conventionally provided in the prong J, when the prong has been placed in its intended position relative to the electric plug adapter. The movement of the prong J into engagement with the end (6 of the conductor I i and the insertion of the end l of the conductor ll into the outlet receptacle R produces end thrust forces between the conductor H and case In, These thrust forces are effectively resisted by the spur 2| and foot 22in their engagement with their respective recesses 4| and 45.

It will be apparent that the parts of the electric plug adapter of my invention may be easily fabricated and assembled, Also it is apparent that the electric plug adapter has a high degree of practical efficiency notwithstanding its great simplicity.

While I have illustrated and described the best form of my invention now known to me, as required by the statutes, those skilled in the art will readily understand that changes maybe 'made in the disclosed construction, without departing from the spirit of my invention as set forth in the appended claims.

I claim:

1. An electric plug adapter for connecting a service plug to a source outlet receptacle and having a housing case and a connector; the connector comprising two parts of substantially equal length extending in spaced non-contacting relation to each other throughout their lengths I and supported in the housing case for relative movement toward and away from each other;

means extending between the parts for yieldably resisting said relative movement of the parts;

the parts having a pair of facing contacts proximate to one end and a pair of backing contacts proximate to the other end, one of said pairs of contacts adapted to engage an electrical contact of a service plug and the other of said pairs of contacts adapted to engage an electrical contact of a source outlet receptacle; and one of said parts being electrically conductive.

.2. An electric plug adapter for connecting a service plug to a source outlet receptacle and having a housing case and a connector; the connector comprising two strip partsv of substantially equal length extending in spaced non-contacting relation to each other throughout their lengths and supported in the housing case for relative movement toward and away from each other; means extending between the parts for yieldably resisting said relative movement of the parts; the parts having a pair of facing contacts proximate to one end and a pair of backing contacts proximate to the other end, one of said pairs of contacts adapted to engage the electrical contact of a service plug and the other of said pairs of contacts adapted to engage the electrical contact of a source outlet receptacle; one of said backing contacts extending cam-wisefrom the plane of said part into space away from the other part; one of said facing contacts extending camwise from the plane of its part into the space between the parts; and one of saidparts being electrically conductive.

3. An electric plug adapter for connecting a service plug to a source outlet receptacle and having a housing case and aconnector; the con nector comprising two leg parts of substantially equal length and having facing contacts proximate to one end facing each other and backing contacts proximate to the other end in back to back relation to each other; the leg parts extending in spaced non-contacting relation to each other throughout their lengths and supported in the housing case for relative movement toward and away from each other; the leg parts extending parallel to each other in the portions thereof adjacent to and intermediate the facing and backing contacts thereof; a yieldable means extending between the leg parts and positioned proximate to one end thereof for retaining said relative movement of the leg parts; and one of said leg parts being electrically conductive.

4. An electric plug adapter for connecting a service plug to a source outlet receptacle and having a housing case and a' connector as claimed in the preceding claim 3 in which said connector parts and said means extending between the same are integral and formed by bending a strip of metal stock upon itself.

5. An electric plug adapter for connecting a service plug to a source outlet receptacle and having a housing case and a connector as claimed in the precedingclaim 3 in which one of said connector contacts is a cam formed by bending the connector part with which it is associated.

6. An electric plug adapter for connecting a service plug to a source outlet receptacle and having a housing case and a connector; the connector comprising two leg parts of substantially equal length and having facing contacts proximate'to one end facing each other and backing contacts proximate to the other end in' back to back relation to each other; one of said leg parts being electro-conductive and flexible along its length; yieldable means engaging the flexible leg part for supporting the same for constrained translatory. and body flexure movements in the housing toward and away from the other of said leg parts; the facing and backing contacts of the flexible leg part each having a cam surface, the cam surface of the facing contact extending to ward the facing contact 01 the' said other of said leg parts and the cam surface of the backing contact extending away from the backing contact of the said other of the leg parts; the cam surface of the facing contact adapted to engage the prong of a service plug urging the flexible leg part to move away from the said other leg part against the constraint of said yieldable means and the cam surface of the backing contact adapted to engage the contact of a source outlet receptacle urging the flexible leg part to move toward said other leg part against the constraint of said yieldable means and by said conjoint engagement of plug prong and source outlet contacts cause a. flexure of the' flexible leg part along its length to a degree determined by the difl'erence between the movements oi. the facing and backing contacts away from and toward said other leg part in said conjoint engagement; and the housing case having an internal chamber of dimensions relative to the flexible leg part allowing said movements of the flexible leg part.

WM. J. MIILEB.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

